You can varnish over paints and bare wood, but can you apply varnish over stain?
You can apply varnish over the stain because the sealant is a clear top coat that will protect the finish underneath. Also, since the sealant is a clear coat (has no color), it won’t interfere with the wood stain color.
Varnish sticks well to a stained surface because it doesn’t need to penetrate the surface to stick. In addition, it will protect its finish from moisture, water, and scratches.
Stain Dry Time Before Varnish
The stain must fully dry (cure) before you seal it. It takes wood stain 3 days to fully dry cure. However, the cure and dry time depends on the brand, room humidity, and temperature.
For the stain to dry and cure, the solvent must evaporate, and its coating must oxidize (harden). Since water evaporates faster than oil, the water-based stain dries faster.
Sealing it too soon will make the finish sticky and peel off. That’s because once you apply varnish, the evaporation process of the solvent is stopped. Since the solvent can’t evaporate and the paint particles can’t harden, the finish will turn tacky and won’t dry.
So, it’s best to wait until the finish is fully dry (cured) before you seal it.
Related Read: Varnish vs Stain?
How To Apply Varnish Over Stain?
Applying varnish over wood stains is necessary for outdoor surfaces. That’s because it will protect it from harsh weather elements such as rain.
Here are the tools you need:
- Dish Soap
- Sponge or Wire brush
- A bowl of water
- Medium-grit sandpaper
- Fine-grit sandpaper
- Spray gun or paintbrush
- Water-based Primer
- Varnish (Satin, medium, or high-gloss)
1. Prepare the Work Area
First, prep the work area. Bad finishes are often a result of improper preparation.
You must remove nearby objects and cover those objects you can’t move. Use painter’s tape over the parts of the surface you don’t want to apply varnish on.
2. Wash and Clean The Finish
Clean the surface because dust and grease will settle over it while the stain is drying. If the surface or coating is dirty, the sealant won’t stick over it.
To clean it:
- Mix dish soap with water.
- Pour the soapy water over the surface.
- Use a soft brush to clean the surface.
- Rinse with clean water.
If the stain was recently applied, you don’t need to wash it; just use a clean rag to wipe off the surface. Also, if the finish is sealed with a top coat, you must remove it.
3. Scuff The Finish
To help the varnish stick better, you must sand or scruff the stained surface. Sanding will remove the imperfections from the surface and create small ridges to allow the sealant to stick better.
To sand a stained surface, start with 150-grit sandpaper and end with fine-grit sandpaper (220-grit). This helps to achieve a smooth and fine finish.
However, if the finish is flaky, swollen, or loose, it’s best to remove the entire coating rather than sand it. If you apply varnish over a loose or flaky stain surface, the finish will look worn out. To remove old stains from a surface, use a paint-stripping compound.
4. Apply The Varnish
You don’t need to apply a primer because it will cover the color of the existing finish and make it look dull. However, you can apply it if you don’t want the finish color to show after it dries.
To apply varnish, use a sprayer because it will help you cover large areas faster and archive an even finish. You can use a paintbrush or paint roller to apply it too. But since varnish requires detail, you need more than 1 paintbrush.
You must match the stain and varnish types (water and oil types). You can also choose satin, medium gloss, or high-gloss sheen. Apply 2-3 coats of varnish over a stained surface. Wait for each coat to dry before applying the next one.
Mixing Stain With Varnish
You can mix stain and varnish to get a colorful and durable finish. Since varnish is a clear coat, it doesn’t have paint pigments or colorant in the paint coating. Therefore, when dry, it has a transparent finish.
On the other hand, the wood stain has a lot of paint pigments (or colorants) in the paint coating but doesn’t have additives that make it resistant to water or durable. So, if you mix them, you will get a colorful finish resistant to water, moisture, and scratches.
However, you must match their types (oil or water-based). If you mix water-based stain with oil-based varnish, the mixture will be inconsistent and won’t stick.
Applying Stain Over Varnish
You can’t apply stain over varnish unless you remove or sand the sealant first. That’s because the sealant produces a protective layer that repels moisture. And, since wood stain can’t penetrate the surface, it won’t stick.
However, if you sand or remove it, the wood stain will stick. That’s because sanding will create tiny ridges (holes) for the wood stain to soak (penetrate) into. But, the finish won’t be as durable. So, to get the best result, it’s recommended to remove the glossy finish of the sealant first.
So, applying stain over varnish isn’t a good idea. That’s because wood stains are designed to alter the color of wood grain and won’t adhere to it properly. Also, applying it over varnish is a waste. That’s because the stain is not durable or strong, so it will wear off or fade if used over a glossy finish.
Related Read: Does Wood Stain Protect Wood?
You can apply varnish after stain, but its coating must be fully dry, and you must match the type (oil or water-based). Varnish will protect the finish and the surface underneath from water, moisture, scratches, and other damage.
However, you can’t apply stain over varnish because it can’t penetrate its glossy finish.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,